Today's telephone network provides for Operator Services Systems (OSS) to support and assist callers. The traditional Local Exchange Carrier (LEC) OSSs include 0+/alternate billing services, such as calling card services, directory assistance, 0-/assistance, 0-/emergency services, 1+coin sent paid, Intercept service, and 1+hotel/motel calls that require real-time rating. A caller typically invokes an operator service by dialing certain digits or by placing calls from certain stations, such as coin stations or hotel/motel stations. For example, a calling party dials 0 to ask for operator assistance, "411" to ask for directory assistance, or 0+NPA-NXX-XXXX to ask for alternative billing (e.g., calling cards or collect calls).
When a caller dials a specific number, such as 0-, 411, or any number of the form 0+NPA-NXX-XXXX, or when a caller dials any number from certain specific stations, such as coin or hotel/motel, the Originating End Office (OEO) switch that serves the calling number routes the call to the OSS designated by the caller's local service provider. Thus, the OEO owner does not have a choice of OSS providers.
Today's telephone network elements communicate call setup signals in accordance with the Signaling System 7 (SS7) Integrated Digital Network User Part (ISUP) call setup-associated protocol. ISUP, however, does not provide procedures enough to enable an intermediate switch to route local operator services calls to select a particular OSS based on the caller's local service provider and the operator service being requested. The basic call setup ISUP protocol places the called party number (i.e., the dialed digits) into the ISUP Called Party Number parameter digits field. In addition, the ISUP protocol fills the OEO parameter "Nature of Address" (NOA) field with an "operator requested" codepoint when `0` is dialed, and with a different codepoint other than an "operator requested" codepoint when `0` is not dialed. Intermediate switches in the network may only use the contents of the Called Party Number parameter, which includes a digits field and the NOA field, to route the call to the OSS. With the current basic call setup ISUP protocol, the intermediate switches can route these calls to only a single OSS, but have no way of selecting among multiple OSSs and routing to a selected one of them. Alternative methods of routing the calls to new OSSs, which compete with existing OSSs for operator services, may require more network facilities and resources.
Therefore, it is desirable to have methods and systems to overcome the disadvantages to operator services signaling in telephone networks.